From the past, in an electrophotographic field such as a copying machine, a laser printer, and a plain-paper fax machine, a surface-modified metal oxide powder, obtained by treating surface of a metal oxide powder such as fine silica, titania, and alumina with an organic substance, has been widely used as an external additive to improve a toner flowability or to control a frictional charging property.
In the past, it has been disclosed that a surface-modified metal microparticle—having a stabilized frictional charging property obtained by surface treatment concurrently using, together with a hydrophobizing agent, an amine-containing silane coupling agent to control a charge and other amine-containing silane coupling agent to increase stability of a triboelectrostatic charge amount—has been disclosed as the external additive mentioned above (for example, see Patent Document 1). Further, a surface-modified silica microparticle—wherein, the surface thereof has been treated, in the presence of an amine catalyst, with an alkyl (with the size of equal to or smaller than a hexyl group) alkoxy silane with the amount thereof relative to the silica microparticle, an amount of water, and temperature and time of the reaction being controlled so that change of a triboelectrostatic charge amount with an elapse of time after the surface treatment (A/B), may be 1.0 to 2.0—is disclosed (for example, see Patent Document 2).
On the other hand, a synthetic resin is being used in many fields including an electric appliance such as a television, an automobile part, a precision instrument such as an optical lens, an optical disk, an organic glass plate, and a signboard, wherein the synthetic resin has merits in its excellent lightness and strength as compared with a glass product and the like, while it has demerits of easily taking an electrical charge and adhering dust and the like thereto. To solve these problems, a countermeasure has been taken such as to impart conductivity to a member itself by producing the member by using a semiconductive material of a composition added with a conductive additive and to impart an antistatic property onto surface of the member by arranging a film or a coat material obtained by using the foregoing semiconductive material.
As to a method for imparting conductivity, a method using a photo-curable resin composition—concurrently using, for example, an imidazoline surfactant and a salt such as an alkaline metal salt, an alkaline earth metal salt, and an ammonium salt—has been disclosed (see for example, Patent Document 3). Alternatively, a method wherein a conductive inorganic particle such as ATO (tin oxide doped with antimony pentaoxide) is added to an organic binder, and a method using a composition for an antistatic hard coat added with the inorganic particle obtained by treating surface of the foregoing inorganic particle with a silane coupling agent have been disclosed (see for example, Patent Document 4). Still alternatively, a method wherein an onium salt is contained in a resin composition by adding an ionic liquid of various kinds thereto has been investigated (see for example, Patent Document 5).